The invention relates to a dispensing system for petrol pumps, comprising a pump, a dispensing valve in a petrol pump nozzle and an electrically controllable solenoid valve.
Dispensing systems for petrol pumps allowing a preselection of a desired fuel amount are controlled in such a way that a principal valve is closed shortly before the selected value is reached and the remaining fuel amount is pumped through a bypass valve which is then also closed when the selected value has been reached. In dispensing systems as known from the prior art, the two valves are operated separately, for example via two electrically controlled magnets.
The invention, provides a dispensing system for petrol pumps, in which the principal valve and the bypass valve are controlled in a simple and cost-effective manner.
In a dispensing system for petrol pumps, comprising a pump a dispensing valve in a petrol pump nozzle and an electrically controllable solenoid valve, this is achieved in that the solenoid valve includes a directly acting principal valve and a bypass valve arranged so as to bypass the principal valve, and a solenoid drive by which in case of a differential pressure present above the sealing seat of the principal valve at first only the bypass valve is able to be switched to the open position, and only after a pressure compensation has occurred at the sealing seat of the principal valve by the opening of the bypass valve is the principal valve also able to be switched to the open position.
The principal valve and a bypass valve arranged so as to bypass the former are opened via one single electrically controlled solenoid drive. Whether both the principal valve and the bypass valve are opened or whether only the bypass valve is opened is dependent on whether a differential pressure is present above the sealing seat of the principal valve. This provides a simple and cost-effective solution allowing to open only one valve or both valves as required.
In accordance with an advantageous embodiment provision is made that, with the pump active and the dispensing valve opened, the principal valve is closed by momentarily switching the solenoid drive off, and that upon switching the solenoid drive back on it will remain closed due to the differential pressure prevailing above its sealing seat.
In petrol pumps allowing a preselection of a desired fuel amount, this results in that both valves are momentarily closed shortly before the preselected value is reached and the remaining fuel amount is pumped through the bypass valve. The reduced flow via the bypass valve permits the fuel to be metered more exactly.
Further features and advantageous further developments of the invention are apparent from the dependent claims.